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                <a name="asio.overview.model.higher_levels"></a><a class="link" href="higher_levels.html"
                                                                   title="Higher Level Abstractions">Higher Level
                Abstractions</a>
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        The asynchronous model presented in this section provides a basis for defining
        higher level abstractions. Asio builds on this core model to provide additional
        facilities, such as:
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                I/O objects such as <a class="link" href="../networking.html" title="Networking">sockets</a>
                and <a class="link" href="../timers.html" title="Timers">timers</a> that expose
                asynchronous operations on top of this model.
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                Concrete executors, such as the <a class="link" href="../../reference/io_context.html"
                                                   title="io_context">io_context</a>
                executor, <a class="link" href="../../reference/thread_pool.html" title="thread_pool">thread_pool</a>
                executor, and the <a class="link" href="../../reference/strand.html" title="strand">strand</a>
                adapter which guarantees non-concurrent execution of completion handlers.
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                Completion tokens that facilitate different composition mechanisms,
                such as <a class="link" href="../composition/cpp20_coroutines.html" title="C++20 Coroutines Support">C++
                coroutines</a>, <a class="link" href="../composition/spawn.html" title="Stackful Coroutines">stackful
                coroutines</a>, <a class="link" href="../cpp2011/futures.html" title="Futures">futures</a>,
                and <a class="link" href="../../reference/experimental__deferred.html" title="experimental::deferred">deferred
                operations</a>.
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                High level support for C++ coroutines that combines support executors
                and cancellation slots to allow for <a class="link"
                                                       href="../composition/cpp20_coroutines.html#asio.overview.composition.cpp20_coroutines.co_ordinating_parallel_coroutines">easy
                coordination of concurrent asynchronous agents</a>.
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        To allow users to more easily write their own asynchronous operations that
        adhere to this model, Asio also provides the helper function <a class="link"
                                                                        href="../../reference/async_compose.html"
                                                                        title="async_compose">async_compose</a>.
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            <div class="copyright-footer">Copyright © 2003-2022 Christopher M. Kohlhoff<p>
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